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Southern Californians who reside near the mountains, hillsides or canyons live with the risk of a wildfire burning down their homes. But rarely do they think about a fire contaminating their drinking water. Perhaps they should. Just ask residents of Ventura, Santa Paula and Ojai, who must boil their tap water before drinking it, cooking with it or brushing their teeth, the result of the powerful Thomas fire that knocked out portions of their water system Tuesday and grew to 96,000 acres by Thursday.

Groundwater overdraft in the San Joaquin Valley – producer of half the state’s agricultural output – has averaged roughly 1.8 million acre-feet annually since the mid-1980s. Even before the start of the most recent drought in 2011, a few San Joaquin farmers recognized the dire need for sustainable water management and started individually pioneering a groundwater recharge practice that has since gained statewide traction.

California’s primary source of water is at risk because the sea level is gradually rising and will begin to contaminate the Sacramento-San Joaquin River Delta estuary with ocean water. The Sea level is predicted to rise 3 to 7 feet by 2100, depending on how fast Antarctic and Greenland ice melts. A 3-foot rise in sea level would inundate the Delta estuary west of Route 5. A larger catastrophe is also looming because any one of several known potential glacier collapses would significantly exceed current sea level rise predictions.

One of the hard truths revealed by California’s five-year drought is that many small, rural communities lack the resources to adapt to water shortages. In this case, that means both money and expertise. It can be very expensive, for instance, to build a new water treatment plant or connect with one in the next closest town. Even if a community finds the money to build a small treatment plant, it may not have anyone locally with the expertise to operate it.